1. Field of the Invention
The present invention relates to a digital data recording and reproducing apparatus which performs digital encoding compression on various information and records and reproduces the encoding compressed data on and from a non-volatile semiconductor memory card, and more particularly, to a digital data recording and reproducing apparatus which records information data such as a moving image or sound which progresses in a time series manner, on a non-volatile memory card together with error correcting data for the information data, and performs suitable reproduction on information data uncorrectable even with the recorded error correcting data.
2. Description of the Related Art
In recent years, the recording capacities of non-volatile semiconductor memories have been increasing and the recordable amount of data per non-volatile semiconductor memory has been increasing. Non-volatile semiconductor memories having card-like shapes have been developed, and digital still cameras for recording still images and audio recording equipment which use such cards in place of silver-halide film or audio recording magnetic tape have been developed and put into practice.
This type of digital still camera and audio recording equipment converts an analog signal picked up and generated by a photographic camera or a microphone into a digital signal, performs encoding compression on the digital signal to convert the digital signal into data having a predetermined data format, and records the data on the non-volatile semiconductor memory. The non-volatile semiconductor memory has a data storage area divided into plural physical blocks each of which stores a predetermined amount of data, and is capable of managing recording or erasure of data for each of the physical blocks. In general, in order to enable recorded data to be read and edited on computer equipment, the non-volatile semiconductor memory adopts a data format conforming to MS-DOS which is an OS for computer equipment.
A microprocessor converts the encoding compressed recorded data into the data format of MS-DOS and creates management file data relative to the recorded data, and records the corrected encoding compressed recorded data and the management file data on physical blocks of the non-volatile semiconductor memory. Thus, reading and erasure of the recorded data recorded on plural physical blocks are performed by using the management file data.
A specific example of a digital data recording and reproducing apparatus using the non-volatile semiconductor memory will be described below with reference to FIG. 5. FIG. 5 is a block diagram showing the construction of an audio digital data recording and reproducing apparatus.
An audio input circuit 21 of the audio digital data recording and reproducing apparatus 20 shown in FIG. 5 is made of a microphone (not shown) which picks up sound such as music or human voice and generates an analog electrical signal, and an amplifier circuit (not shown) which amplifies the analog audio signal generated by the microphone.
During recording, the analog audio signal generated by the audio input circuit 21 is converted to a digital audio signal by an analog/digital conversion circuit (hereinafter referred to as the A/D circuit) 22, and the digital audio signal is supplied to an encoding compression circuit 23. The encoding compression circuit 23 performs encoding compression on the digital audio signal, thereby generating predetermined digital compressed data. The encoding compression in the encoding compression circuit 23 uses the compression technique of G729A which is an ITU (the International Telecommunications Union) standard. The digital encoding compressed data generated by the encoding compression circuit 23 is recorded on a card provided with a non-volatile semiconductor memory (hereinafter referred to as the non-volatile memory card) 25, via a control means 24 composed of a microprocessor (MPU). As is well known, the microprocessor is also called CPU, and is made of one chip on which are integrated various units such as an arithmetic unit which performs arithmetic and logic operations, a control unit which performs interpretations of instructions and generation of control signals, and a storage unit. The control means 24 exerts control on writing and reading of the digital encoding compressed data to and from the non-volatile memory card 25, and also generates management data on the written digital encoding compressed data.
During reproduction, the digital encoding compressed data read from the non-volatile memory card 25 under the control of the control means 24 is expanded and decoded by a decoding expansion circuit 26, whereby the digital encoding compressed data is converted to a digital audio signal. The digital audio signal generated by the decoding expansion circuit 26 is converted to an analog audio signal by a digital/analog conversion circuit (hereinafter referred to as the D/A circuit) 27, and the analog audio signal is supplied to an audio output circuit 28 which serves as an output end made of an amplifier circuit and a speaker (none of which is shown).
An operating switch 29 and a liquid crystal display 30 are connected to the control means 24. The operating switch 29 serves as an operation input meanswhich has a switch for entering an operation input, such as audio recording, audio reproduction or power-off, into the audio digital data recording and reproducing apparatus 20. The liquid crystal display 30 displays the operating state of the audio digital data recording and reproducing apparatus 20 according to the input from the operating switch 29.
Incidentally, the non-volatile memory card 25 is capable of being removably fitted into a card slot provided in the body (not shown) of the audio digital data recording and reproducing apparatus 20.
The A/D circuit 22, the encoding compression circuit 23, the decoding expansion circuit 26 and the D/A circuit 27 are formed as a one-chip audio processing integrated circuit (hereinafter referred to as the audio processing IC).
If the non-volatile memory 25 used in the audio digital data recording and reproducing apparatus 20 has a recording capacity of, for example, 8 Mbytes, the data recording area of the non-volatile memory 25 is managed in the state of being divided into 1,024 physical blocks (8 Kbytes per physical block) as shown in FIG. 6A. Each of the physical blocks is managed in the state of being divided into plural pages (page 0 to page end) (in the case of 8 Mbytes, one physical block is divided into sixteen pages 0 to 15).
As shown in FIG. 6A, each of the pages of the physical blocks of the non-volatile memory card 25 has a data area of 512 bytes and a redundant part of 16 bytes. As shown in FIG. 6B, the data area includes a data area 1 made of 256 bytes 0 to 255 and a data area 2 made of 256 bytes 256 to 511. As shown in FIG. 6C, the 16 bytes of the redundant part include bytes 512 to 515 assigned to a reserve area, byte 516 assigned to a data status area, byte 517 assigned to a block status area, bytes 518 to 519 assigned to a block address area 1, bytes 520 to 522 assigned to an error correcting data area (hereinafter referred to as ECC area) 2, bytes 523 to 524 assigned to a block address area 2, and bytes 525 to 527 assigned to an ECC area 1. The data area 1 and the data area 2 correspond to the ECC area 1 and the ECC area 2, respectively.
When the audio digital data recording and reproducing apparatus 20 is to record digital encoding compressed data on the non-volatile memory card 25 having such data recording areas, an analog audio signal inputted from the audio input circuit 21 is encoding-compressed and converted into digital encoding compressed data by the audio processing IC 31, and the control means 24 executes control so that the digital encoding compressed data is recorded on the data area of each page of physical blocks of the recording area of the non-volatile memory card 25. At the same time, the control means 24 generates redundant part data relative to the digital encoding compressed data recorded on the data area, and records the redundant part data on the redundant part of the same page.
On the other hand, when the audio digital data recording and reproducing apparatus 20 is to read and reproduce data recorded on the non-volatile memory card 25, the control means 24 reads the data recorded on the non-volatile memory card 25, in the page order of each of the physical blocks, and makes a check as to the presence or absence of an error in the data of the data area of each page by using the data of the ECC area of the redundant part. If there is an error in the data of the data area, the error is corrected with the data of the ECC area. The data of a data area having no error or error-corrected data is decoded and expanded by the audio processing IC 31 and outputted via the audio output circuit 28.
However, the error correcting data recorded in the ECC area of each page of each physical block of the non-volatile memory card 25 is basically set so that error correction is performed on the data recorded in the data area of the same page, but the data recorded in the data area do not always have error contents which are completely correctable with the error correcting data.
If the data error of the data area of a page cannot be corrected with the data of the ECC area of the redundant part of the same page, the control means 24 repeatedly reads the same page having the data error, so that the control means 24 cannot read and reproduce the data of pages following the page having the data error.
As described above, in the related-art digital data recording and reproducing apparatus which records digital encoding compressed data on a non-volatile memory card on the basis of information continuously progressing in a time series manner, and which reads, decodes and expands the digital encoding compressed data recorded on the non-volatile memory card and provides a reproduced output, the digital encoding compressed data are recorded on the non-volatile memory card together with error correcting data for the digital encoding compressed data, and the digital encoding compressed data is error-corrected with the error correcting data. However, if the digital encoding compressed data contains an error uncorrectable with the error correcting data, the related art apparatus operates to perform error correction while repeatedly reading the data of a recording area in which the uncorrectable error data is recorded. This leads to the problem that the related art apparatus becomes unable to read and reproduce digital encoding compressed data subsequently to the recording area which contains the error, and becomes incapable of reproducing the recorded digital encoding compressed data.
The invention aims to provide a digital data recording and reproducing apparatus in which during reproduction of digital encoding compressed data recorded on a non-volatile memory card, even if there appears digital encoding compressed data containing an error uncorrectable with error correcting data, it is possible to read and reproduce data following the digital encoding compressed data having the uncorrectable error.
The invention provides a digital data recording and reproducing apparatus which comprises: a recording and reproduction control means for executing exchange of digital encoding compressed data between a digital encoding compression means which converts analog information which consecutively progresses in a time series manner into digital encoding compressed data as well as a digital decoding expansion means which decodes and expands the digital encoding compressed data and a non-volatile memory card on which to record digital encoding compressed data, and recording the digital encoding compressed data in a predetermined area of the non-volatile memory card and also reading digital encoding compressed data from the non-volatile memory card; a digital data writing control means for, during recording of the digital encoding compressed data generated by the digital encoding compression means, generating error correcting data for the digital encoding compressed data and also converting the digital encoding compressed data and the error correcting data into a predetermined format of file data, and writing the predetermined format of file data into a predetermined recording area of the non-volatile memory card, the digital data writing control means being provided in the recording and reproduction control means; a digital data decoding control means for, during reproduction of file data recorded on the non-volatile memory card, executing control to read the file data, perform error correcting processing on the digital encoding compressed data on the basis of error correcting data contained in the file data, decode and expand the digital encoding compressed data after the error correction processing by means of the digital decoding expansion means irrespective of whether the error correcting processing determines that the digital encoding compressed data contains no error or the digital encoding compressed data is error-corrected by the error correcting processing, convert the decoded and expanded digital data into an analog signal, and output the analog signal, the digital data decoding control means being provided in the recording and reproduction control means; and an output means for outputting consecutively in a time series manner the analog signal into which the decoded and expanded digital signal is converted.
According to the first aspect of the invention in the above-described digital data recording and reproducing apparatus, during recording of digital encoding compressed data generated by the digital encoding compression means, error correcting data for the digital encoding compressed data is generated, and the digital encoding compressed data and the error correcting data are converted into a predetermined format of file data and written into a predetermined recording area of the non-volatile memory card. During reproduction of the file data written to the non-volatile memory card, the file data is read out, and error correction is performed on the digital encoding compressed data on the basis of the error correcting data contained in the file data. The digital encoding compressed data after the error correction processing is decoded and expanded by means of the digital decoding expansion means irrespective of whether the digital encoding compressed data contains no error or is error-corrected. Accordingly, during reproduction of digital encoding compressed data recorded on the non-volatile memory card, even if there appears digital encoding compressed data containing an error uncorrectable with the error correcting data, the uncorrectable digital encoding compressed data is decoded, expanded and reproduced on xe2x80x9cas-isxe2x80x9d basis without being repeatedly read out, and data other than the uncorrectable data can be correctly read out and reproduced.
According to the second aspect of the invention, in the above-described digital data recording and reproducing apparatus of the first aspect of the invention, the digital data writing control means generates the digital encoding compressed data and the error correcting data in units of recording pages of a recording area of the non-volatile memory card, and converts the digital encoding compressed data and the error correcting data into the predetermined format file data, whereas the digital data decoding control means executes control to read the file data in units of the recording pages, perform error correction on the digital encoding compressed data on the basis of the reproduced error correcting data, decode and expand the digital encoding compressed data after the error correction processing by means of the digital decoding expansion means irrespective of whether the digital encoding compressed data contains no error or the digital encoding compressed data is error-corrected, convert the decoded and expanded digital encoding compressed data into an analog signal, and output the analog signal.
According to the second aspect of the invention in the above-described digital data recording and reproducing apparatus, the recording of the file data on the non-volatile memory card and the reproduction of the file data from the non-volatile memory card are performed in units of pages which are physically divided in the non-volatile memory card, and the error correction of reproduced digital encoding compressed data is also performed in units of pages.
In addition, during the reproduction, the error correction of the digital encoding compressed data is performed on the basis of reproduced error correcting data, and the digital encoding compressed data after the error correction processing is decoded and expanded by means of the digital decoding expansion means irrespective of whether the digital encoding compressed data contains no error or is error-corrected. Accordingly, even if there appears digital encoding compressed data containing an error uncorrectable with the error correcting data, the uncorrectable data page is not repeatedly read out and the digital encoding compressed data is decoded, expanded and reproduced on xe2x80x9cas-isxe2x80x9d basis, but data other than the uncorrectable data can be correctly read and reproduced. Since the uncorrectable page is decoded and expanded in small units like units of pages and a meaningless sound is only reproduced for a small period in units of pages, a user does not easily notice the meaningless sound based on the error data and can infer the contents of the meaningless sound on the basis of sounds which precede and succeed the meaningless sound.
According to the third aspect of the invention, the above-described digital data recording and reproducing apparatus according to the first aspect further comprises a muting means for controlling an operation of the output means, the digital data decoding control means executing control to cause the muting means to inhibit the output means from outputting the analog information when the digital encoding compressed data contains error data which cannot be corrected by the error correcting processing.
According to the third aspect of the invention, in the above-described digital data recording and reproducing apparatus, during reproduction, if the digital encoding compressed data contains uncorrectable error data, the muting means provided for the output means which outputs analog information inhibits the output means from outputting the analog information.
The fourth aspect of the invention also provides a digital data recording and reproducing apparatus which comprises: a recording and reproduction control means for executing exchange of digital encoding compressed data between a digital encoding compression means which converts analog information which consecutively progresses in a time series manner into digital encoding compressed data as well as a digital decoding expansion means which decodes and expands the digital encoding compressed data and a non-volatile memory card on which to record digital encoding compressed data, and recording the digital encoding compressed data in a predetermined area of the non-volatile memory card and also reading digital encoding compressed data from the non-volatile memory card; a digital data writing control means for, during recording of the digital encoding compressed data generated by the digital encoding compression means, generating error correcting data for the digital encoding compressed data and also converting the digital encoding compressed data and the error correcting data into a predetermined format of file data, and writing the predetermined format of file data into a predetermined recording area of the non-volatile memory card, the digital data writing control means being provided in the recording and reproduction control means; a digital data decoding control means for, during reproduction of file data recorded on the non-volatile memory card, executing control to read the file data, perform error correcting processing on the digital encoding compressed data on the basis of error correcting data contained in the file data, decode and expand by means of the digital decoding expansion means the digital encoding compressed data which is regarded as having no error in the error correcting processing or is error-corrected by the error correcting processing, processing of the digital encoding compressing data being skipped if the digital encoding compressed data contains data uncorrectable with the error correcting processing, convert the decoded and expanded digital data into an analog signal, and output the analog signal, the digital data decoding control meansbeing provided in the recording and reproduction control means; and an output means for outputting consecutively in a time series manner the analog signal into which the decoded and expanded digital signal is converted.
According to the fourth aspect of the above-described digital data recording and reproducing apparatus, during recording of digital encoding compressed data generated by the digital encoding compression means, error correcting data for the digital encoding compressed data is generated, and the digital encoding compressed data and the error correcting data are converted into a predetermined format of file data and written into a predetermined recording area of the non-volatile memory card. During reproduction of the file data written to the non-volatile memory card, the file data is read out, and error correction is performed on the digital encoding compressed data on the basis of the error correcting data contained in the file data. If the digital encoding compressed data contains an uncorrectable error, such digital encoding compressing data is skipped, but the digital encoding compressed data which contains no error or is error-corrected is decoded and expanded by means of the digital decoding expansion means. Accordingly, during reproduction of digital encoding compressed data recorded on the non-volatile memory card, even if there appears digital encoding compressed data containing an error uncorrectable with error correcting data, the uncorrectable digital encoding compressed data is skipped without being repeatedly read out, whereby data other than the uncorrectable data can be correctly read out and reproduced. Moreover, since the uncorrectable data is skipped, a meaningless sound is not reproduced.
According to the fifth aspect of the invention in the above-described digital data recording and reproducing apparatus according to the fourth aspect, the digital data writing control means generates the digital encoding compressed data and the error correcting data in units of recording pages of a recording area of the non-volatile memory card, and converts the digital encoding compressed data and the error correcting data into the predetermined format file data, whereas the digital data decoding control means executes control to read the file data in units of the recording pages, perform error correction on the digital encoding compressed data on the basis of the reproduced error correcting data, decode and expand by means of the digital decoding expansion means only a page of the digital encoding compressed data which is regarded as having no error in the error correcting processing or is error-corrected by the error correcting processing, the page of the digital encoding compressing data being skipped if the page of the digital encoding compressed data contains data uncorrectable with the error correcting processing, convert the decoded and expanded digital encoding compressed data into an analog signal, and output the analog signal.
According to the fifth aspect of the invention in the above-described digital data recording and reproducing apparatus, the recording of the file data on the non-volatile memory card and the reproduction of the file data from the non-volatile memory card are performed in units of pages which are physically divided in the non-volatile memory card, and the error correction of reproduced digital encoding compressed data is also performed in units of pages.
In addition, during the reproduction, the error correction of the digital encoding compressed data is performed on the basis of reproduced error correcting data, and a page which contains uncorrectable data error is skipped, and the digital encoding compressed data of only a page which contains no error or is error-corrected is decoded and expanded by means of the digital decoding expansion means. Accordingly, even if there appears digital encoding compressed data containing an error uncorrectable with error correcting data, the uncorrectable data page is skipped without being repeatedly read out, but data other than the uncorrectable data can be correctly read and reproduced. Since the uncorrectable data is skipped in small units like units of pages, a user does not easily notice the lack of the skipped portion and can infer the contents of the skipped portion on the basis of sounds which precede and succeed the skipped portion.